Rice treating process



Oct.. 10, 1950 w. w. JONES Erm. 2,525,137

RICE TREATING PROCESS Filed sept. 2'5, 1946 Harn/Pv Son KEI? DEM/EPEE 7 l2 nu? nrrmaspuse/ TEMPERATURE 22 @4Q/my@ Patented Oct. 10, 1950 RICE TREATING PROCESS Watkins W. Jones and George W. Brewer, Sacramento, and Alva B. Court, San Francisco, Calif., assignors to Rice Growers Association of California, Sacramento, Calif., a corporation of California Application September 23, 1946, Serial No. 698,736

8 Claims. (Cl. 99-80) This invention relates to a rice paddy treating process and has for one of its main objects an improved process for treating the rice paddy prior to milling so that the breakage in the milling process will be reduced.

Another obj ect of the invention is an improved process for treating the rice paddy prior to milling so that the rice will resist breakage in the milling process and so that the grains will be substantially undistorted and substantially free from white spots. Y

A still further object is a processA for moving the ric'e paddy along a path of travel and during said movement treating the paddy by soaking, steaming' under pressure, and cooling and partially drying the paddy under atmospheric temperature, in succession, each step being controlled as to time and temperature so thaty the finished product will be ready for being dried and milled in the conventional manner, without substantial distortion and .breakage of the grains and which grains will be substantially free from white spots. Y A,

I-Ieretofore, as disclosed. in copending application Serial No. 588,726 filed April 16, 1 945, Patentv No. 2,515,409 issuedJuly 18, 19,50, the parboiling of lpaddy preparatory to Amilling the rice has been done inbatches and under, times and temperatures that diiier from those hereinv given. While the finished product under the process disclosed in said application wasV commercially acceptable and the grains were morenniform in shape and color than prior to that time, the present process results in noticeably greater uniformity in'color and shape and in freedom from susceptibility to breakage of grains-in milling. Also, testsunder governmental supervision clearly show `that the rice treated by the present processis` at least the equivalent if not greater in food values toA that produced under the process disclosed in the above copending application.

TheV drawingis illustrative of the steps of the process as well as being diagrammatic of appa' ratus adapted to carry outthe process.

In detail, after the paddy rice has been cleaned of chaff, seeds, etc.,- it is conveyed by an elevator I, to the elevated end of a horizontally elongated, rotary soaking drum 2 and is deposited into said end together with water at a temperature of between about 180 F. and 200 F., preferablyy closer to the latter. The paddy and water move through this drum together, the drum being heat insulated to maintain thetemperature of the Water as uniformes possible. VFrom between 2 t about and 15 minutes time is required for the paddy to move through drum 2.

At the discharge or lower end-of drum 2 the paddy and a substantial amount of water is discharged into a collector tank 3 that may be surrounded by a hot water jacket 4 to keep up the y temperature, `and from this tank the paddy and water is pumped through a pump 5 and through a dewatering device 6 and then into the upper end of a slightly inclined horizontally elongated steamer drum 1 in which a steam pressure of between about 10 and 15 lbs. per square inch is maintained during rotation oi the drum and movement ofthe paddy from the upper to the lower end of the latter.` A pressure of about l2 lbs. per square inch is preferred.

The dewaterer may comprise a generally hori-V zontally disposed rotary screen 9 that extends through the upper end of enclosed tank I0 and through which screen the paddy is moved into the steamer drum 1. The steam pressure in the drum is therefore also in screen 9, but the head of water and paddy at the pump prevents escape of the steam. In the dewatering device the water will drain from the paddy, which draining is facilitated by the replacement of the water in the body of paddy in screen 9 by the steam. The water and steam condensate then passes through a heat exchanger II where the temperature of the water is'reduced to between about 180 F. and 200 F. (preferably nearer the latter) andV is pumped by a pump I2 back through pipe I3 to the head end of the soaking tank for reuse.

About 30 to 35 minutes is required for the paddy to move through the steamer drum 1, andY the paddy is constantly agitated by rotation ofV the drum during this time so all of the paddy will be uniformly exposed to the steam.

The paddy is then substantially constantly dischargedfrom the discharge end of tank 1 into one or the other of a, pair or more of decompression chambers I4, I5. Valves I6, I'I close the lowery ends of said chamber respectively, while valves I8, I9 close the upper ends of said chambers.

In operation the pressure in the steamer 1 and in the decompression chamber into which the paddy is being discharged are the same or about twelve pounds. For example, in the drawing, valve I6 in chamber I4 is shown vclosed while valve I8 at the top of said chamber is open, and the rice paddy is flowing into chamber I4. Valve I9 at the top of chamber I5 is closed. Thereiorethe steam pressure in chamber I4 will be .the same as in the steamer.

termined level, which may be determined by suitable automatic controls, the valves I8, I1 will be closed and valve I9 will open, whereupon the paddy from the steamer will flow into the chamber I and as chamber I5 will be in communication with the steamer 1, the pressure in said chamber will be the same in the steamer, or from to 15 lbs. per square inch, but preferably about 12. A selector gate may be provided and suitably controlled for deflecting the flow of paddy from one chamber to the other according to which of the valves I8, I9 are open.

As soon as the valve I8 closes (referring to the operation as illustrated) a valve 2l will open just suiliciently to reduce the steam pressure ill chamber I4 to about 3 to 4 lbs. per square inch (preferably about 4 lbs.) over a period of from about 3 to 4 minutes time. sure is desirable to prevent rupture of the cells, expansion of rice, and distortion of the latter.

The paddy may remain in chamber I4 under the 3 to 4 lbs. pressure for aV relatively short time, but as soon as the pressure has dropped to 3 to 4 lbs., the valve I6 may be opened and the paddy from chamber I4 discharged into the upper end of a horizontally elongated slightly inclined rotary cooler 22.

Insofar as chambers I4, I5 are concerned, they will alternately fill and empty in the above described manner, a valve 23 being also provided t.

for chamber I5l for functioning in the same manner as valve 2|. It is manifest that the ow from steamer 'l' into one or the other of the decompression chambers is constant, and a continuous flow from some one of theV decompression chambers l may be effected by regulation of the capacity and number of said chambers and the rate of ow therefrom. However, there will be Van interruption of the flow amounting to from 3 to 4 minutes in order to gradually reduce the pressure on the paddy. This does not reduce the'volume of paddy passing continuously through the soaker, steamer and cooler, however, inasmuch as the decompression chambers will ll and empty with suiiicient rapidity to take care 0f the maximum capacity of the soaker and steamer.l

The rotary' cooler 22 may be provided Iwith the Conventional iliehts t0 continuously lift the paddy and d rop the saine during the travel of the paddy through the cooler to its lower en d, and during said travel, a current oi;` atmospheric air is drawnv through the cooler counter to the general directional movement of the paddy by meansn of a suction fan 25.l The paddy will remain in the coolerV about 3 to '7 minutes, inasmuch as this is sufficient time4 to prepare the paddy for being dried in the conventional rice driers which do not form part of this invention. vOrdinarily about i-ve minutes will reduce the temperature of the paddy and also remove the surface moisture. The paddy itself will contain from about to .35% moistureV when discharged` from the cooler.v Unless this surface moisture is removed, the paddy would` be too sticky to handle. satisfactorily in the subsequent drying step.

The product resulting from the above process (including the iinal usual drying step) mills with y the minimum of breakage, thereby producing a large yield of bead rice. Also, rice grains are substantially free from distortion, and the objectionable white spots or white bellies, and the food values are far greater Ythan in ordinary milledY rice. In appearance, the grains are more of a translucent character than opaque, and have This slow Vreduction in prese.

none of the chalky characteristics of most rice. The grains are very hard, and do not cook up any faster than the ordinary rice, and while the dried product has a slightly tan or yellowish cast, it will be restored to the usual whiteness upon being cooked.

Before concluding, it may be pertinent to note that there is practically no variation in the steam pressure in the steamer when one or the other of the decompression chambers is placed in communication therewith.

It is to be understood that the detailed description and drawings are not to be considered restrictive of the invention, but merely illustrative f of a preferred form thereof.

In some installations it has been found quite advantageous to introduce air into the dewaterer at the same pressure as the steam in the steamer through line 30 so that the air will replace the surface water that fills `the voids or interstices between the paddybefore the paddy goes into the steamer, This reduces the amount of condensation of steam lin the dewaterer without loosing steam pressure. This replacement of the water in the paddy at this point is very important.

From the foregoing it will be seen that the rice paddy moves continuously along an enclosed path of travel in which path it is Successively soaked, freed from surplus water inthe interstices between the'individual paddy units g steamed under pressure, removed from such pressure and freed from surface moisture as well as partially cooled. The rice-paddy can be comfortably handled by hand after it passes through Athe,v rotary cooler,

l the latter, however, being chiefly concerned with removing the surface moisture. By causing the paddy to fall through the current of air in the.

factory method of performing this step.

We claim:

1. A process of treating rice paddy for milling that comprises the steps of soaking the paddy in water having a` temperature between about F. and 200 F. for a' period between about ten and Afifteen minutes,l then removing the paddy from the. water and subjecting it, to steam under a pressurebetween about 10 and 15 lbs. per square inch for 'a period of time between about 30 and 3,5 minutes,I Vthen progressively reducing the pressure to `atmospheric pressure, then removing surfa'ce' moisture from said paddy and reducing its temperature.

2. A process of treating` rice paddy for milling that comprises the steps' of soaking the paddy in water having a temperature between about 180 F. and 200 F. for a period between about ten and fifteen minutes, then yremoving the paddy from the water-and subjecting it to steam under a pressure between about lovand 15 lbs. per square inch for a period of time between about 30 and 35 minutes, and constantlyl agitating said paddy during said steaming, then-,progressively reducing the pressure to atmospheric pressure, then removingsurface moisture'from said paddy andreducing its` temperature.

3..A process of treating rice paddy for milling that comprisesthe stepsof soaking the paddy in water having a temperature between about 180"'F.4 and` 200 for a period between` about ten and fifteen minutesthen removing the paddy 30 and 'l'minutes,l then' p'rogresrsi'velyv reducing the pressure `to atmospheric pressure, then removing surface moisture from said paddy and reducing its temperature, by subjecting said rice to a current of vair at atmospheric temperature for a period of between about 3 and 7 minutes.

4. A process of treatingk rice paddy for milling that comprises the steps of soaking the paddy in water having a temperature between labout 180 F. and 200 F. for a period -between about ten and fteen minutes, and constantly agitating said paddy during said soaking, then removing the paddy from the water and subjecting it to steam under a pressure between about and 15 lbs. per square inch for a period of time between about 30 and 35 minutes, then progressively reducing the pressure to atmospheric pressure then removing surface moisture from said paddy and reducing its temperature.

5; A process of treating rice paddy for milling that comprises the steps of soaking the paddy in water having a temperature between about lll 180J F. and 200 F. for a period between about ten `and iiiteen minutes, then removing the paddy from the water and subjecting it to steam under Y a pressure between about 10 and 15 lbs. per square inch for a period of time between about and 35 minutes, and constantly agitating said paddy during said steaming, then progressively reducing the pressure to atmospheric pressure, then removing surface moisture from said paddy and reducing its temperature, by subjecting said rice to a current of air at atmospheric temperature for a period of between about 3v and 7 minutes.

6. -A process of treating ricepaddy for milling that comprises the steps of soaking the paddy in water having a temperature of between about 180 F. and 200 F. for about twelve minutes, then removing the paddy from the water by draining the water therefrom and thereafter subjecting said paddy to steam under a pressure between about 10 and 15 lbs. per square inch for a period of time between about 30 and 35 minutes and causing a constant tumbling and agitation of the paddy during said steaming, then progressively reducing said presure to between about 3 and4lbs. per square inch over a period of about 4 minutes, nally reducing said pressure to atmospheric pressure and then partially drying and cooling said paddy. l

7. A process of treating rice paddy for milling that comprises substantially continuously mov ing said paddy along a substantially enclosed path of travel and during said movement and in succession, soaking the paddy in water of a temperature of between about F'. and 200 F. for a period of about 12 minutes, removing free water from said paddy, subjecting said paddy to steam pressure of between about 10 and 15 lbs. per square inch for between about 30 and 35 minutes, slowly reducing said pressure to about 4 lbs. per square inch and thereafter to atmospheric pressure, removing surface moisture from said paddyl and reducing its temperature a predetermined degree.

8. In the process of treating rice paddy for milling the steps of; moving said paddy along an enclosed path ofv travel, successively soaking said paddy in water of a temperature of from about 180 F. to about 200 F. for about fifteen minutes, replacing surplus surface soak-water with an elastic fluid, steaming said paddy under about ten to fifteen pounds pressure for about thirty to thirty-five minutes, removing the rice from said steam and pressure, and removing surface water from the paddy by causing said paddy to fall through a current of air during the movement of thepaddy in said path, said paddy being in continuous movement during the aforev said steps. f

WATKINS W. JONES. GEORGE W. BREWER. ALVA B. COURT.

. REFERENCES CITED The following references are of record in the rile of this patent: Y

UNITED STATES PATENTS OZai-Durrani Apr. 6, 1948 

1. A PROCESS OF TREATING RICE PADDY FOR MILLING THAT COMPRISES THE STEPS OF SOAKING THE PADDY IN WATER HAVING A TEMPERATURE BETWEEN ABOUT 180*F. AND 200*F. FOR A PERIOD BETWEEN ABOUT TEN AND FIFTEEN MINUTES, THEN REMOVING THE PADDY FROM THE WATER AND SUBJECTING IT TO STEAM UNDER A PRESSURE BETWEEN ABOUT 10 AND 15 LBS. PER SQUARE INCH FOR A PERIOD OF TIME BETWEEN ABOUT 30 AND 35 MINUTES, THEN PROGRESSIVELY REDUCING THE PRESSURE TO ATMOSPHERIC PRESSURE, THEN REMOVING SURFACE MOISTURE FROM SAID PADDY AND REDUCING ITS TEMPERATURE. 